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The new Space Launch System (SLS) NASA is developing is useful for robotic science missions as well as human spaceflight according to the director of the Space Telescope Science Institute (STScI).

Testifying to a House subcommittee last week, Matt Mountain said that SLS could enable launching telescopes much larger than the Hubble Space Telescope or the upcoming James Webb Space Telescope (JWST). STScI operates Hubble and will operate JWST after it is launched in 2018. Mountain described telescopes with primary mirrors 15-25 meters across -- three or four times the size of JWST -- that might be able to detect life on planets around other stars that would be enabled by a launch vehicle the size of SLS coupled with "human or robotic infrastructure to assemble such a system in space." Another science mission that would benefit from an SLS-type rocket is the long-awaited Mars sample return mission, he added.

That comes with two big caveats, however. First, SLS flights would have to be relatively frequent, at least once a year, he said. Second, the cost of using SLS could not be borne by whatever science mission needs it. Those funds would have to come from elsewhere in NASA. Mountain cited the two decades of Hubble history as a precedent. Hubble was launched by the space shuttle in 1990 and five astronaut teams serviced it between 1993 and 2009. "The cost of the space shuttle for Hubble was not fully borne by the Science Mission Directorate, but rather provided as part of NASA's space flight infrastructure for use by the entire agency," he explained. Science should be an "essential and exciting partner" in NASA's exploration activities, but "cannot drive the development of human spaceflight systems."

The main purpose of the September 12, 2012 hearing before the Subcommittee on Space and Aeronautics of the House Science, Space and Technology Committee was getting an update from NASA and industry officials on the status of the SLS and the Orion spacecraft. The SLS/Orion system will launch astronauts to destinations beyond low Earth orbit (LEO).

Dan Dumbacher, NASA's deputy associate administrator for exploration systems development, assured the subcommittee that SLS is on track for its first test launch in 2017 and first launch with a crew in 2021. The Orion spacecraft similarly is on schedule, he said, for a first test launch in 2014 aboard a Delta IV rocket, followed by a second test on the first SLS flight in 2017, and the first crewed flight in 2021. Jim Chilton of Boeing, the prime contractor for SLS, and Cleon Lacefield of Lockheed Martin, prime contractor for Orion, generally agreed.

Chilton, however, called development of the SLS core stage a "challenge." Although the SLS engines and boosters come from the space shuttle program and the upper stage from the Delta IV program, the core stage is a "clean sheet design," he said. Another challenge, he added, is that NASA is being held to a flat budget profile meaning that "simultaneous development of all the elements needed to get to the final configuration ... won't be possible."

Dumbacher expressed confidence, however, that NASA will be able to pull it all together.

Rep. Hansen Clarke (D-MI) asked what impact the Continuing Resolution (CR) for the first six months of FY2013 will have on the SLS and Orion programs. Dumbacher said he had been given guidance to plan for 50 percent of what those programs received in FY2012, but pointed to continuing uncertainty about FY2013 funding. He stressed that funding stability is critical. "Changes to or instability in the funding forces replanned work, re-work ... and all of that effort takes away from our ability to actually execute ... and build the program."

What level of funding SLS and Orion would receive under the CR apparently is an issue. The day after the hearing, Reps. Ed Perlmutter (D-CO) and Lamar Smith (R-TX) wrote a letter to NASA Administrator Charlie Bolden and White House Office of Management and Budget (OMB) Acting Director Jeffrey Zients urging them to keep the programs funded at their FY 2012 levels. The letter says: "Unfortunately we have received indications that efforts are underway within NASA and OMB to reduce or slow down the rate of funding....This would be a major mistake."